Occupational Outlook Handbook - Best place to start looking for background information! Articles also have citations provided, which will make it easier to cite in Noodletools.
Career One Stop - Click on "Explore Careers" then "Career Clusters" for great background on different types of jobs.
Learn How to Become - Great overview on career information with mostly updated information.
Apprenticeship USA - Detailed government website on apprenticeships and apprentice programs.
City and Town Info. - Informative page / cite on career background information, salaries and opportunities by city / state.
O*Net Online - Additional background info. on all types of careers. Sposored by the US Department of Labor.